Subject: + mm-hotplug-remove-stop_machine-from-try_offline_node.patch added to -mm tree To: toshi.kani@xxxxxx,isimatu.yasuaki@xxxxxxxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,kosaki.motohiro@xxxxxxxxxxxxxx,liwanp@xxxxxxxxxxxxxxxxxx,rafael.j.wysocki@xxxxxxxxx,tangchen@xxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 14 Aug 2013 15:50:19 -0700 The patch titled Subject: mm/hotplug: remove stop_machine() from try_offline_node() has been added to the -mm tree. Its filename is mm-hotplug-remove-stop_machine-from-try_offline_node.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-hotplug-remove-stop_machine-from-try_offline_node.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-hotplug-remove-stop_machine-from-try_offline_node.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Toshi Kani <toshi.kani@xxxxxx> Subject: mm/hotplug: remove stop_machine() from try_offline_node() lock_device_hotplug() serializes hotplug & online/offline operations. The lock is held in common sysfs online/offline interfaces and ACPI hotplug code paths. try_offline_node() off-lines a node if all memory sections and cpus are removed on the node. It is called from acpi_processor_remove() and acpi_memory_remove_memory()->remove_memory() paths, both of which are in the ACPI hotplug code. try_offline_node() calls stop_machine() to stop all cpus while checking all cpu status with the assumption that the caller is not protected from CPU hotplug or CPU online/offline operations. However, the caller is always serialized with lock_device_hotplug(). Also, the code needs to be properly serialized with a lock, not by stopping all cpus at a random place with stop_machine(). This patch removes the use of stop_machine() in try_offline_node() and adds comments to try_offline_node() and remove_memory() that lock_device_hotplug() is required. Signed-off-by: Toshi Kani <toshi.kani@xxxxxx> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memory_hotplug.c | 31 ++++++++++++++++++++++--------- 1 file changed, 22 insertions(+), 9 deletions(-) diff -puN mm/memory_hotplug.c~mm-hotplug-remove-stop_machine-from-try_offline_node mm/memory_hotplug.c --- a/mm/memory_hotplug.c~mm-hotplug-remove-stop_machine-from-try_offline_node +++ a/mm/memory_hotplug.c @@ -1694,9 +1694,8 @@ static int is_memblock_offlined_cb(struc return ret; } -static int check_cpu_on_node(void *data) +static int check_cpu_on_node(pg_data_t *pgdat) { - struct pglist_data *pgdat = data; int cpu; for_each_present_cpu(cpu) { @@ -1711,10 +1710,9 @@ static int check_cpu_on_node(void *data) return 0; } -static void unmap_cpu_on_node(void *data) +static void unmap_cpu_on_node(pg_data_t *pgdat) { #ifdef CONFIG_ACPI_NUMA - struct pglist_data *pgdat = data; int cpu; for_each_possible_cpu(cpu) @@ -1723,10 +1721,11 @@ static void unmap_cpu_on_node(void *data #endif } -static int check_and_unmap_cpu_on_node(void *data) +static int check_and_unmap_cpu_on_node(pg_data_t *pgdat) { - int ret = check_cpu_on_node(data); + int ret; + ret = check_cpu_on_node(pgdat); if (ret) return ret; @@ -1735,11 +1734,18 @@ static int check_and_unmap_cpu_on_node(v * the cpu_to_node() now. */ - unmap_cpu_on_node(data); + unmap_cpu_on_node(pgdat); return 0; } -/* offline the node if all memory sections of this node are removed */ +/** + * try_offline_node + * + * Offline a node if all memory sections and cpus of the node are removed. + * + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call. + */ void try_offline_node(int nid) { pg_data_t *pgdat = NODE_DATA(nid); @@ -1765,7 +1771,7 @@ void try_offline_node(int nid) return; } - if (stop_machine(check_and_unmap_cpu_on_node, pgdat, NULL)) + if (check_and_unmap_cpu_on_node(pgdat)) return; /* @@ -1802,6 +1808,13 @@ void try_offline_node(int nid) } EXPORT_SYMBOL(try_offline_node); +/** + * remove_memory + * + * NOTE: The caller must call lock_device_hotplug() to serialize hotplug + * and online/offline operations before this call, as required by + * try_offline_node(). + */ void __ref remove_memory(int nid, u64 start, u64 size) { int ret; _ Patches currently in -mm which might be from toshi.kani@xxxxxx are mm-hotplug-remove-unnecessary-bug_on-in-__offline_pages.patch mm-hotplug-verify-hotplug-memory-range.patch mm-hotplug-remove-stop_machine-from-try_offline_node.patch linux-next.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html